Changing SliverAppBar title color in Flutter application

You can do it using a ScrollController , listen to the scroll and compare the offset with the default size of the Toolbar.I made an example for you:

            class TestingNewState extends State<TestingNew> {              ScrollController _scrollController;              bool lastStatus = true;              _scrollListener() {                if (isShrink != lastStatus) {                  setState(() {                    lastStatus = isShrink;                  });                }              }              bool get isShrink {                return _scrollController.hasClients &&                    _scrollController.offset > (200 - kToolbarHeight);              }              @override              void initState() {                _scrollController = ScrollController();                _scrollController.addListener(_scrollListener);                super.initState();              }              @override              void dispose() {                _scrollController.removeListener(_scrollListener);                super.dispose();              }              @override              Widget build(BuildContext context) {                return NestedScrollView(                  controller: _scrollController,                  headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {                    return <Widget>[                      SliverAppBar(                        expandedHeight: 200.0,                        floating: false,                        pinned: true,                        backgroundColor: Colors.white,                        flexibleSpace: FlexibleSpaceBar(                            centerTitle: true,                            title: Text("text sample",                                style: TextStyle(                                  color: isShrink ? Colors.black : Colors.white,                                  fontSize: 16.0,                                )),                            background: CachedNetworkImage(                              imageUrl:                                  'http://preprod.tibib-live.com/medias/cached-media/medium/5bea5964109aa-c827b05facc3781485e584dac2f4dddc.png',                              fit: BoxFit.cover,                            )),                      ),                    ];                  },                  body: Center(                    child: Text("hello world"),                  ),                );              }            }